Hydraulic emergency brake for pneumatic brake systems



y '14, 1953 F. s; scHAADT 2,645,313

HYDRAULIC EMERGENCY BRAKE FOR PNEUMATIC BRAKE SYSTEMS Filed Nov. 25, 1950 2 Sheets-Sheet 1 u If i '33 1Q lit. 1: Li

, INVENTORL FRANCIS s. SCH/MDT ATTOR July 14, 1953 F. s. SCHAADT HYDRAULIC EMERGENCY BRAKE FOR PNEUMATIC BRAKE SYSTEMS Filed Nov. 25, 1950 2 Sheets-Sheet 2 ATTOR/VE Patented July 14, 1953 HYDRAULIC EMERGENCY BRAKE FOR PNEUMATIC BRAKE SYSTEMS Francis, S. Schaadt, San Francisco, Calif. Application November 25, 1950, Serial No. 197,591

The present invention relates to vehicle brakes and particularly to a hydraulic brake system to be used as an auxiliary or emergency brake on vehicles such as large trucks, trailers'and busses which employ pneumatic brakes.

Many large vehicles have pneumatic brake systems but only a mechanical emergency brake that is inadequate for emergency purposes when the vehicle is under way at high speedor carrying a heavy load. Furthermore, the. mechanical emergency brake is carried only by the powered vehicle so that where trailers or semi-trailers are used, the pneumatic system is relied upon entirely in the trailer unit. Pneumatic systems, are subject to failure because of bursting or leakage of the many necessary conduits through which pressure is transmitted and many accidents result from these failures.

It is an object of the present invention to provide a hydraulic brake system for use in conjunction with a pneumatic brake system and to provide a hydraulic system normally held out of operation but automatically brought into operation upon failure of pressure in the pneumatic system.

Another object of the invention is to provide a hydraulic brake for vehicles or the like in which tional pneumatic brakes and with hydraulic emergency brakes embodying the present invention;

Fig. 2 is an enlarged sectional view taken on the line 11-11 of Fig. 1;

Fig. 3 is a sectional view taken on the line IIIIII of Fig. 1; and

Fig. 4 is a schematic view illustrating hydraulic and pneumatic circuits. 7

Referring first to Fig. 1 of the drawings, the frame of a trailer chassis is shown at as supported by sets of rear wheels ll carried by an axle I2, there being the usual spring assembly indicated at 13 in Fig. 3 interposed between the frame and axle; The wheels II are provided with brake drums shown at 14 within which the usual brake shoes are provided. The brake shoes are not herein illustrated as they form no part i 2 Claims. (01. 188-152.)

' a lever 2| fixed to the shaft I5.

of the present invention and it will sufllce to an understanding of this invention to know that the brakes used are spread apart or urged into contact with the drum for braking action by rotary or oscillatory movement of a shaft l5 which is supported for rotation as in a bearing bracket 15 clamped to the axle, as best shown in Fig. 2, by means of bolts indicated at H.

Each of the shafts I5 is adapted to be rotated or oscillated to effect application of the brakes by means of a pneumatic cylinder IS with. a piston rod i9 adapted to be projected when pneumatic pressure is supplied to the cylinder. The end of the rod I9 is connected as by a clevis with All of the foregoing structure is conventional and is subject to the objection heretofore mentioned that failure of pneumatic pressure leaves the vehicle entirely without braking power.

Accordingto the present invention, a hydraulic ram or jack, such as indicated at 22, is also ap plied to oscillate each of the shafts l5 and apply the brakes. Each of the jacks 22 is supported by a bracket 23, see Fig. 2, secured to the axle 12, if desired, by clamping means similar to that which carries the bearing bracket l6. Each of the hydraulic jacks 22 has an extendable piston rod 24 with a bifurcated fitting 25 at its outer end. This fitting 25 embraces a lever 26 fixed to the shaft it so that upon extention of the piston rod 24 when hydraulic pressure is introduced to the jack, the shaft l5 will be oscillated to. apply the brakes. However, when the hydraulic system is not in use, oscillation of the shaft i5 by the pneumatic system will be accompanied by swinging movement of the lever 26 without effecting the hydraulic jacks 22 because the lever is free to move in the bifurcated fitting 25. It is also desirable that the hydraulic system be enabled to oscillate the shaft [5 without effecting the pneumatic cylinders and to obtain this result, the lever 2i actuated by the pneumatic brake system may be connected to the shaft l5, as shown in Fig. 2, through a collar 23 fixed tothe shaft and having an arcuate cut-away portion 29. The hub of the lever 21 has an inwardly projecting segment which fits into but is smaller than the cutaway portion 29 and normally abuts one end of the cut-away portion as illustrated in Fig. 2. With this construction, swinging of the lever 2| toward the right to apply thebrakes will rotate the collar 28 and shaft l5. However upon application of the brakes by the hydraulic system, the shaft and collar are free to oscillate in a right hand direction as viewed in Fig. 2 without depend from the frame of the vehicle.

34. A discharge conduit communicating with ing mechanism. The power shaft 42 carries friction rollers shown at 45 in Fig. 1 adapted to be brought into engagement with the tread surface of the tires on the wheels I l. A single roller may be employed to engage one tire but on a dual,

wheel vehicle, a greater frictional advantage is obtained by the use of two rollers as shown. The pump 32 and the bearings for the shaft 42 are both mounted on a platform 49 pivotally supported as by apin 41 in brackets 48 which may A spring 50 is interposed between the pivoted platform 45 and a spring seat 51 is secured to the vehicle frame and normally tends to urge downwardly that end of the platform which supports the shaft 42 and brings the rollers 45 into frictional contact with the vehicle wheels. end of the platform a pneumatically actuated jack 53 is interposed between the platform and a pad 54 also secured to the frame of the vehicle so that when the jack is extended by pneumatic pressure, the platform is swung in the opposite direction to compress the spring 50 and hold the rollers 45 out of contact with the wheels of the vehicle.

The hydraulic and pneumatic circuits and the manner in which the emergency brake operates are best illustrated in Fig. 4 of the drawings. In this figure, the pneumatic cylinder 18 which operates the air brakes is shown as supplied with air under pressure from a compresser schematically illustrated at 55. A valve 5'! controlled by a foot pedal 58 in the drivers cab controls pneumatic pressure through a conduit 59 for operating. the brakes at will. A' branch conduit 60 communicates air under pressure to the jack 53 for holding the hydraulic system out of operation as previously described. In the event of failure of the compresser or loss of pressure in the lines 59 and 60 from any cause, the pneumatic pressure inv the jack 53 fails and the spring 50 swings the platform 46 downwardly so that the drive shaft .42 is driven by frictional contact of the drums 45 with the wheels ll. Consequently the normally idle hydraulic pump 32 is driven to circulate fluid through the hydraulic system and the brakes may I be actuated hydraulically through the foot pedal At the opposite I 39. If for any reason it becomes desirable to employ the hydraulic system for actuating the brakes while pressure remains in the pneumatic system, a valve 62 in the line is operable as by a hand lever 63 in the cab to discontinue the supply of pneumatic pressure to the jack 53 and to vent pressure from the jack. When this has been done, either one or both of the systems may- For trailer brakes, the mechanical linkage may,

of course, be replaced by electromagnetically actuated valves or other devices commonly used for this purpose wherein no rigid mechanical connection is necessary between the truck and the trailer unit.

I claim:

1. .An emergency brake for vehicles with a fluid actuated first system which comprises a second fluid system for applyingthe brakes, said second system comprising a pivoted platform, a fluid pump on the platform, drive means for the pump comprising a roller engageable with a ground engaging wheel of the vehicle .to be driven thereby when the vehicle is in motion, resilient means normally pivoting the platform toward such roller engaging position, and a fluid jack opposing said resilient means and supplied with pressure from said first named fluid system whereby upon failure of pressure in said first system the second system will become operable.

2. An emergency brake for vehicleswith a fluid actuated first system which comprises a second fluid system for applying the brakes, said second system comprising a pivoted platform, a fluid pump on the platform, drive means for the pump comprising a roller engageable with a ground engaging wheel of the vehicle to be driven thereby when the vehicle is in motion, resilient means normally pivoting the platform toward such roller engaging position, a fluid jack opposing saidresilient means and supplied with pressure from said first named fluid system whereby upon failure of pressure in said first system the second system will become operable, and valve means to relieve pressure from said jack without relieving pressure from said first system.

FRANCIS S. SCI-IAADT;

References Cited in the file of this patent UNITED STATES PATENTS Hollerith Jan. 3, 1950 

